1. Field of the Invention
The present invention relates generally to capturing a still image using images stored separately at predetermined times in addition to a preview image and, more particularly, to an apparatus and method for storing high-resolution images received at predetermined times in a first buffer and capturing a still image using the high-resolution images stored in the first buffer.
2. Description of the Related Art
An ordinary digital camera includes a lens system for forming an image of a subject on a film or a surface of an image sensor, and the image sensor for detecting the image formed by the lens system as an electrical signal. The film or the surface of the image sensor corresponds to an image surface of the lens system. A focus of the lens system varies in position according to a distance between the lens and the subject. Therefore, it is possible to capture or photograph images of various qualities according to changes in the position of the image surface, which is associated with a position of the subject.
A user photographs a desired subject in an image using a digital camera with the above-stated elements. In order to more easily take a picture of a desired subject, the user may use a preview image that provides an image of the subject in real time, to previously get hold of the image to be captured. The preview image is displayed on a display through the lens system in real time, and the user may easily take a picture of the desired subject while viewing the displayed preview image. A camera with the function of outputting a preview image on the display is the necessaries of life, playing an important role in multimedia communication required in the modern society.
An internal structure of a common camera outputting a preview image will be described with reference to FIG. 1 below.
FIG. 1 shows an internal structure of a conventional camera outputting a preview image. Elements of the camera include a lens system 101, an image sensor 103, a driver 111, an Image Signal Processor (ISP) 105, a display 107, and a controller 109.
Referring to FIG. 1, the lens system 101 optically receives an image of a subject, and includes at least one lens. The image sensor 103 converts the image of a subject optically received by the lens system 101 into an electrical signal. The ISP 105 processes the electrical signal received from the image sensor 103 on a frame-by-frame basis, and outputs a low-resolution image frame that is converted according to screen features (size, picture quality, resolution, etc.) of the display 107.
The display 107 displays the low-resolution image frame received from the ISP 105 on a screen, and the driver 111 moves the lens system 101 according to control of the controller 109. Although not shown in the drawing, the driver 111 includes a motor for providing a driving force, and a carrier for moving the lens system 101 forward and backward by the driving force. The controller 109 controls the driver 111 to move the lens system 101 to a focal position.
Now, a description will be made of a procedure for receiving and analyzing a preview image using the elements in FIG. 1.
When an image of a subject is optically received through the lens system 101, the image sensor 103 converts the optically received image of a subject into an electrical signal and provides the electrical signal to the ISP 105. The image of a subject received through the lens system 101 is continuously received in real time, and the image sensor 103 converts the received real-time image of a subject into an electrical signal, and provides the electrical signal to the ISP 105. The ISP 105 converts the received real-time image of a subject into a low-resolution preview image and displays the low-resolution preview image on the display 107. The user may monitor the received real-time preview image on the display 107.
Commonly, however, when a user captures an image while viewing a preview image, an image following the preview image is captured. If the subject is stationary, it doesn't matter even though an image is captured after the time the user intends to take a picture of the subject. However, in case of an image sensitive to motion, an unwanted image may be captured after the time the user intends to take a picture.